While many had predicted China would top both categories, the Americans go into the second week with realistic chances of finishing with the most gold and most total medals.

After Saturday night's competition, the U.S. led by one medal in each list — totaling 26 golds and 54 overall.

Behind the two powerhouses, the battle for the next few spots has thrown up some surprises, with South Korea surging into the top four and Russia and Australia lagging behind expectations.

Britain picked up six golds on Saturday — including three in track and field by Jessica Ennis (heptathlon), Mo Farah (10,000 meters) and Greg Rutherford (long jump) — to bring its total to 14 gold and 29 overall, third in both categories.

The U.S. has won the overall medal count at the last four Summer Games, but China has gained ground.

China grabbed the most golds at its home Olympics four years ago in Beijing with 51, while the United States was a distant second with 36. The Americans won the overall count with 110 medals, 10 more than the Chinese.

Going into Saturday night's events, the United States was leading China 24-23 in gold medals, while the Chinese were ahead 50-48 in the overall.

"We are a little bit behind where we were in Beijing, but we are still having really good performances," U.S. Olympic Committee spokesman Patrick Sandusky said. "It's gone back and forth the last three or four days. We may go up at night, China may go up in the morning, but obviously China is still very strong."

While the USOC is reluctant to project medal counts, the aim is always the same.

"Our goal coming into the games was certainly to finish top of the medal count and we are having good progress but you know we are not taking anything for granted," Sandusky said. "We are still only halfway through."

The final week of the games will be dominated by medal events in track and field, where the United States is much stronger than China. USA Track & Field is targeting 30 medals overall. U.S. hopes took a hit Sunday when LaShawn Merritt pulled up in his heat with a hamstring injury, ruling him out of defending his 400-meter title.

"I think the USA will come out ahead by a little bit in both races — medals and golds," Olympic historian and medals tracker Bill Mallon said.

Former Italian Olympic official Luciano Barra predicts medals based on performances at the most recent world championships. Coming into London, he projected that China would top both medals charts but now believes the tables have been turned.

"The U.S. is improving on their results," Barra said. "Yes, China is still very strong. But I think the U.S. can win the most number of gold and total medals. It's a surprise, but I think that can happen."

Sebastian Coe, the former two-time 1,500-meter champion who runs the London organizing committee, raised eyebrows in the U.S. when he told The Associated Press in April that he thought China would beat the United States in the medals race.

He tempered that Saturday in another AP interview, saying: "It is going to be a China-USA fight for No. 1."

The Russians, who finished third in Beijing with 23 gold and 73 total medals, have been a bust so far with only three gold. But the Russians have 28 overall and still have strong contenders in track and field, wrestling, rhythmic gymnastics and boxing. They should still finish third by the end of the games.

"I don't want to say anything now, but in some sports we will draw very serious conclusions," he told Russian media. "Now it is practically like a war. The main thing is to get to the end, and we'll draw the conclusions later."

Alexander Zhukov, head of Russia's Olympic Committee, said the nation's hopes should be kept in check.

"It seems to me that the expectations of many of our fans are too high: only gold!" he said. "I read (Britain's) Daily Telegraph every day and the British have no such expectations. With them, if someone gets into the final he's already a hero, and everyone writes about him. And our folks say: You're happy with a bronze! I'm astonished."

Spots four through seven look to be a fight among Britain, Germany, South Korea and France.

Host Britain, which finished fourth in Beijing with 19 gold and 47 total, has been targeting the No. 4 spot again this time. Team GB hopes to pick up more medals in sailing, equestrian, boxing, tae kwon do and track.

"We are under no illusion," British Olympic Association spokesman Darryl Seibel said. "There is a long way to go and the competition won't be backing off. After the success Team GB experienced in Beijing, we aren't catching anyone by surprise. We are benefiting from the support of the home crowd. We'll need that the rest of the way."

South Korea has been a surprise with 17 total and nine gold, including three in archery and others in judo, shooting and fencing.

"Team Korea is making great achievements ... above the level of what was predicted," said Park Yong-sung, head of the South Korean Olympic Committee. "We are experiencing great hope in new sports such as fencing. This is very encouraging."

France (8-22), Germany (5-21) and Italy (5-13) are also doing well. North Korea has been another surprise with four gold medals, including three in weightlifting.

No one has been more disappointed than the Australians. Before coming to London, the Australian Olympic Committee said it wanted to finish in the top five of both medals tables but is way off that projection.

Australia had only one gold and was well outside the top 10 in both categories. Worse yet, South Pacific neighbor and traditional rival New Zealand had three golds. The last time Australia finished behind New Zealand in gold medals was in 1984.

"In terms of our top-five finish, it's still a mathematical possibility," Australian team chief Kitty Chiller said. "We're not panicking. We're not worried. Sure there's a few medals we have missed out on but there's a lot more to come."